This invention relates to sensing a condition for a laundry apparatus, and is particularly concerned with methods and apparatus for sensing the moisture content of a multi-layered load within a dryer and controlling the operation of the dryer as a function thereof.
Resistance sensing of moisture in the surface of fabrics, typically clothing fabrics, is widely used and well known in clothes dryers. As moisture transfers from the inner section of single thickness fabric items to the outer surface, the moisture is removed from the surface by air and heat mechanisms. As soon as the surface is sufficiently dry, the resistance of the outer surface, as measured by a resistance sensor, changes in an amount sufficient to indicate dryness.
A problem occurs with resistance sensing, though, when the article has a greater thickness, such as a velour blanket, a comforter or a shoe. A problem also occurs when the article is made up of various different materials since the resistive sensing approach may sense the outer surface of one type of material as being dry. The inner portion of the item, such as a shoe innersole, however, could still be damp just below the dry surface due to the various layers of materials. Accordingly, moisture might remain in the article since it cannot migrate to the surface as readily as moisture can be removed from the top surface, resulting in damp clothing or over-drying of the article to insure dryness.
Shoes, in particular, defy effective resistive moisture sensing. Many shoes, especially athletic shoes, have an insole insert which consists of a fabric covering positioned on a molded foam rubber insole pad. This pad may possess such other features as an instep support. Beneath the insole insert is found an insole board, which is usually a fibrous pad, approximately 1.5-2.0 mm thick. The insole board typically covers small depressions in the molded outsole and generally provides uniform support to the insole insert. The insole board also absorbs moisture and tends to retain it rather well in known dryers presently used. Accordingly, because of the multi-layered construction of the foam rubber insole pad, when submitted to the typical drying process, the insert""s top cloth surface can be detected as dry. The sub-surface foam rubber pad and insole, however, can still be wet.
Thus, prior to wearing shoes which have been wet, the user typically allows the shoes to dry, either by air drying or using a known dryer system. Air drying, however, requires a lot of time, while known dryer moisture detection systems indicate that the insert""s cloth surface can be dry while the sub-surface foam rubber pad and the insole board can still be wet.
A need therefore exists for measuring the moisture content of a multi-layered load such as shoe interiors. The solution, however, must be capable of detecting moisture in material below the outer surface of the load. The solution must also operate the drying operation based on the moisture content. Further, the solution must be capable of detecting sub-surface moisture when the surface is dry. Further, a need exists for an efficient process to prevent overdrying of the load. The solution, however, must be capable of drying such a load to a wearable dry condition, but not to over dry, which could cause component material such as leather to lose natural oils leading to cracking. A need further exists for an efficient process of measuring the moisture by sensing the moisture content inside shoes such as below the soles. The solution, however, must efficiently support the shoes in the dryer.
Dryers currently available often apply resistance sensing. U.S. Pat. No. 4,422,247 uses two sensor strips, which when bridged by wet clothing, serve as a resistance (impedance) to discharge a charged capacitance. Since wet clothing has a lower resistance than dryer clothing, wet clothing will discharge the capacitance more quickly. By measuring the voltage of the capacitance at a predetermined time after contacting the clothing, the dryer then correlates wetness with remaining capacitance voltage via a basic R-C circuit, which in turn prevents a timer from advancing toward the off position. This system, though, does not solve the current need since it is not effective in sensing moisture just below the surface of multi-layered fabrics such as shoe interiors because the surface resistance of the cloth increases exponentially as dryness is reached. Accordingly, lower resistance just below the surface may exist, especially in bulky clothing or shoe soles, where a foam rubber material may exist just below the fabric liner of the sole.
Another typical known device comprises a drying rack working in conjunction with the resistance sensing strips. This drying rack is supported within the dryer but remains stationary, rather than rotating with the drum of the dryer. Therefore, items placed upon the rack are subjected to the heat of the dryer, but arc not tumbled with the rotating drum. The physical configuration of the sensors does not allow detecting of shoe interior surfaces and the sensing system works best with surface drying. Accordingly, the dryer cannot effectively sense the interior moisture content of the shoes.
Another prior art dryer rack comprises sensors connected to the rack wherein the shoes are placed on top of the rack. This drying rack, however, does not solve the current need since the sensors incorporate the resistance sensing previously mentioned. Further, this type of drying rack does not solve the current need since the sensors are not placed inside the shoes to measure the moisture within multiple layers.
U.S. Pat. No. 5,903,222 discloses an additional prior art moisture detector. This invention teaches a device for detecting wetness in diapers using a capacitance sensor. In this invention, the sensors are completely enclosed within a housing which is attached to the external surface of the diaper. Since the sensors must face the rear of the housing, the sensors do not contact the diapers. This device, however, does not solve the current need since the device does not contact the articles. Accordingly, the device would not effectively sense the moisture of multi-layered materials having diverse compositions for each layer.
The present invention provides for a condition sensor for a laundry apparatus, in particular, a condition sensor that measures the moisture content in a multi-layered load.
To that end, the invention provides a device and method that efficiently and economically determines the moisture content of items, such as shoes, and signals operating controls to the dryer based on the moisture content.
Described in the accompanying drawings and following text is a condition sensor that measures the moisture content of the multi-layered load based on measuring the permittivity of the load, rather than a resistance of the surface of the load. This configuration leads to improved drying of multi-layered loads. Thus, the present invention disclosed herein provides a condition sensor which overcomes many of the inadequacies of dryers known in the art.
In an embodiment, the present invention provides a condition sensor device for a dryer. The housing of the dryer encloses a drum wherein an air moving device, which is operated by a dryer control, directs a stream of air through the drum. A capacitance sensor located within the drum measures the permittivity of a non-tumbling load positioned within the drum. The capacitance sensor then communicates with the dryer control to control the operation of the air moving device based on the measured permittivity of the load.
In an embodiment, the present invention provides a device for a dryer comprising a base and a condition sensor connected to the base wherein the condition sensor is operative to sense a condition of the load positioned within the dryer. The condition sensor comprises at least one support connected to the base wherein the at least one support has at least one extension attached thereto.
A pair of capacitance sensors are attached to the at least one extension with the pair of capacitance sensors being arranged to build up charge through the condition sensor, charge level dependent on the moisture content of the load positioned in the dryer. The invention also provides a circuit arranged to receive, read and generate signals in response to the charge of the capacitance sensors.
In an embodiment, the present invention provides a condition sensing device for sensing the moisture content of a load placed in a dryer wherein a base is removably connected to the dryer.
In this embodiment, a condition sensor is connected to the base. The condition sensor which senses the moisture content of the load while the load is being dried by the dryer comprises a pair of supports positioned on the base wherein a pair of capacitance sensors are attached to each support to contact the load.
Further, the pairs of capacitance sensors are arranged to build up charge based on the permittivity of the load and a circuit is arranged to receive, read and generate signals in response to the charge of the capacitance sensors.
In an embodiment, the permittivity of the load is a function of the moisture content of the load. Additionally, the charge of the pair of capacitance sensors varies in relation to the permittivity.
In an embodiment, the present invention provides a fabric drying apparatus which senses the moisture content of a non-tumbling load placed in the treatment zone during the drying operation and adjusts the drying operation based on the moisture content. This embodiment comprises a dryer and a base connected to the dryer wherein the base is positioned to extend into the treatment zone of the dryer when the door is in a closed position.
Further, a condition sensor is connected to the base with the condition sensor being operative to sense the moisture content of the load while the load is being processed by the dryer. The condition sensor comprises a pair of supports positioned on the base with each support having a pair of extensions attached to support the load. Additionally, a pair of capacitance sensors are attached to each pair of the extensions wherein each pair of capacitance sensors are positioned to contact the load and are arranged to build up charge based on the permittivity of the load.
The present invention further provides method of sensing the moisture content of the multi-layered load in a dryer. The method provides positioning the multi-layered load on a condition sensor and initiating a drying operation. Next, the method provides sensing the moisture content of the multi-layered load by measuring the permittivity of the multi-layered load during the drying operation.
The method further provides increasing the charge of the condition sensor in relation to the permittivity of the multi-layered load and communicating the charge of the condition sensor to a circuit. Based on the charge, operating signals are then sent to the dryer.
An advantage of the present invention is to sense the moisture content of multi-layered loads in the dryer.
Another advantage of the present invention is to sense the moisture content of multi-layered loads having different material compositions.
Another advantage of the present invention is sense the moisture content of a layer below a dry surface layer.
Another advantage of the present invention is to use capacitance sensing to sense the moisture content of multi-layered loads.